RE: #1) I’m not sure I fell similarly about the dark sky. I tend to agree more with the idea that one could learn to love an empty sky as much as the stars, not out of a residual effect of the stars but due to a newfound appreciation of total dark. One consideration: as Frost hinted, the stars die every morning and we are often left with an empty sky. Granted, it is blue and not black, but it is interesting that in stanza 2 he mentions the daytime and immediately follows it with the hypothetical situation of stars dying. These two are in many ways the same event. It seems to suggest that because he doesn’t miss the stars during the day there is no reason he should miss them at night.
But…… thinking about it further, why does Auden feel the need to replace his admiration? I think I’m liking Alan’s general theory applied to this situation. I’ll leave that to Alan. Regardless, if we take his affection to be a template for general human affection, it might point to a necessity of loving at night (during the bad times, maybe?).